This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-362535, filed Nov. 29, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a pipe coupling for connection to an associated pipe for feeding, in particular a fluid such as paint.
2. Description of the Related Art
Conventionally, this type of pipe coupling comprises a plug and a socket mutually connected to each other. The socket comprises a ball type valve body having a through hole formed to allow the plug to be inserted therein, a main cylindrical body having a fluid passage formed therein, an annular sealing member provided at a forward end portion in a concentrical relation to the fluid passage, and a valve body seating surface formed at the forward end of the sealing member with the valve body arranged thereon, and a casing fixed to the main cylindrical body to surround and support the valve body in a rotatable way. A long hole for allowing the plug to be inserted into the through hole of the valve body is formed in the casing such that it is opened from the side surface toward the top area of the casing and that a wider area is provided at the side surface opening portion of the long hole in the casing and a narrower area is provided at the top area opening portion. The plug has an anti-slippage bulged portion insertable into the long hole at the wider area and latchable to the side edge of the long hole at the narrower area. By inserting the plug into the through hole of the valve body at the wider area of the long hole and, from this state, rotating the plug to the narrower area at the top area of the long hole, the plug is connected to the socket. With the rotation of the plug, the valve body is also rotated and, when the plug is rotated to the narrower area at the top area of the long hole, the through hole of the valve body is aligned with the fluid passage of the main cylindrical body to make the fluid passage of the plug communicate with the fluid passage of the main cylindrical body.
According to the so-structured pipe coupling, the valve body surrounded with, and supported by, the casing is freely rotatable and no restriction is made to its rotation direction. In the case where, however, any shock is exerted on the valve body at a washing of the socket or due to some cause or other, the valve body is rotated, causing the through hole of the valve body to be displaced out of alignment with the long hole of the casing, that is, to be slipped out of the long hole. In this case, it becomes difficult to insert the plug from the long hole into the through hole of the valve body. Further, when the plug is set in the connected state, the plug is not withdrawn out of the socket, thus presenting a problem.
An object of the present invention is to provide a pipe coupling for ensuring an easier connection and separation of the plug to and from the socket.
Another object of the present invention is to provide a pipe coupling which can lock a plug and socket in a mutually-connected state.
According to the present invention, there is provided a pipe coupling comprising a socket including a main cylindrical body having a forward end section and an axial bore for allowing a fluid to pass therethrough, an annular valve seat fitted into the forward end section of the main cylindrical body in a concentrical relation to the axial bore, a ball type valve body arranged to be rotatable relative to the valve seat and having a through hole, and a casing fitted over the main cylindrical body and rotatably retaining the valve body in cooperation with the valve seat. The casing has a cylindrical side surface, a top area and a long hole extending from the side surface toward the top area and having a wider area formed at the side surface and a narrower area situated at the top area, and the valve body allows the through hole to communicate with the axial bore of the main cylindrical body when the through hole is aligned with the narrower area of the long hole and to close the axial bore when the through hole is aligned with the wider area of the long hole. The pipe coupling further comprises a plug having an outer periphery and a bulged portion situated on the outer periphery and passable through the wider area of the long hole and not passable through the narrower area. The plug is inserted into the through hole of the valve body through the wider area of the long hole, and is connected to the socket in a mechanical and fluid-communication way when the plug is moved along the long hole to the narrower area together with the valve body. The pipe coupling further comprises a guide for guiding the valve body along the extending direction of the long hole from a position in which the through hole is aligned with the wider area.
According to this pipe coupling, the valve body is guided along the extending direction of the long hole and, even if a force is exerted on the valve body due to some reason or other, the through hole is located within the long hole. By doing so, it is possible to easily and positively confirm the position of the through hole of the valve body and hence to easily insert and withdraw the plug into and out of the socket.
Preferably, the guide has a slide section for guiding the valve body to allow the through hole to move along the extending direction of the long hole and a latching section for restricting the rotation of the valve body to allow the through hole to move between a position in which the through hole is aligned with the wider area of the long hole and a position in which the through hole is aligned with the narrower area of the long hole. Since the valve body has its rotation restricted by the latching section, it is possible to positively locate the valve body to a required position and easily and smoothly insert and withdraw the plug into and out of the socket.
It is useful to provide a lock at least on one of the plug and socket whereby it prevents the plug from being moved when the plug is set to the narrower area of the long hole. In this case, even if a force is exerted on the plug for some reason or other, the plug is not moved from the narrower area and it is possible to positively prevent an unauthorized withdrawal of the plug out of the socket.
Preferably, the slide section has a first planar surface formed on the inner surface of the casing in a manner substantially parallel to the extending direction of the long hole, and a second planar surface formed on the valve body to be set in contact with the first planar surface. Preferably, the latching section is formed on the inner surface of the casing and on the valve body and has first engaging portions mutually engaging in a position in which the through hole is aligned with the wider area of the long hole and second engaging portions mutually engaging in a position in which the through hole is aligned with the narrower area of the long hole.
In the case where the first and second engaging portions have planar surfaces respectively extending in a direction substantially orthogonal to the extending direction of the long hole, the valve body can be accurately and positively located relative to the casing.
Preferably, the lock as set out above has a sleeve fitted over the plug and movable along an axial direction and the casing has a sleeve-latchable projection on the peripheral portion of the narrower area. This sleeve may be urged by a spring toward the forward end of the plug or have an internally threaded section engageable with an externally threaded section on the outer peripheral surface of the plug.